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Electronics and Communication Engineering

3rd year

6th

Semester

May /June 2014 Examination

Question Paper

EC2353/EC 63/10144 EC604-Antennas and Wave

Propagation

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Part A

1. What is the significance of radiation resistance of an antenna?

2. Draw E and H plane radiation pattern of a dipole.

3. Compare short dipole from half wave dipole.

4. What are the advantages of antenna arrays?

5. What is called method of imaging?

6. State field equivalence principle.

7. Why frequency independent antennas are called so?

8. Mention any two applications of turnstile antenna.

9. Differentiate virtual height from actual height.

10. What are the effects of ground on low frequency wave transmission?

Part B

11 a)1] Define the following parameters and their dependence on antenna performance.

1) Radiation pattern,2)input impedance,3)polarization.(8)

2] Derive the magnetic field components of a dipole having the dimension l

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Or

b) With neat diagram explain the principle of parabolic reflector antenna and various

types of feed used.(16)

14) a)1]Explain the measurement of antenna gain(8)

2] With necessary illustrations explain the radiation characteristics of Yagi Uda

antenna.(8)

Or

b) With suitable diagram explain the construction and principle of Helical antenna in

different mode of operation.(16)

15)a)1]Explain the ground wave propagation of radio waves(8)

2] Write notes on faraday rotation.(8)

Or

b) 1]Describe the space wave propagation and explain the importance of line of sight

propagation.(8)

2] Explain the following terms with diagram

1) Duct propagation,2)Critical frequency,3)Skip Zone.